SYSTEM AND METHOD FOR DETECTING MOISTURE

Description

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Corrosion under insulation is problematic in many environments. In oil and gas production plants, process plants, refineries, and chemical plants, for example, corrosion under insulation can be a serious threat to plant integrity. Management of the corrosion under insulation problem can be extremely challenging, because water ingress is difficult to reliably predict and many types of insulation systems can be affected. Additionally, regular inspection and maintenance is difficult and costly, typically involving removal of insulation from process piping. Sometimes, the inspection and maintenance techniques can require shutdown of the plant process.

Description of Related Art

[0002] Moisture sensors exist but have drawbacks that limit their usefulness in many environments susceptible to corrosion under insulation. Conventional moisture sensors, constructed as point devices using coated, metalized surfaces that undergo a change in electrical impedance when exposed to moisture, are not practical for use in a process environment. Some sensors measure rate of heat dissipation to determine moisture content in a medium, while other sensors measure changes in electrical resistance of an element exposed to moisture, but none of these sensors is practical for use in many process and plant environments. For example, some of these sensors are not particularly helpful in providing guidance as to specific areas of concern along, for example, sections of insulated pipe. Another moisture sensing technique detects hydrogel-induced micro bending in fibers, but such techniques also have limited applicability in process and plant environments. For example, such techniques can be limited to environments in which temperatures only rise to approximately 50°C. US4978229 describes a system that makes use of a pair of groups of thermocouples. EP0989396, US3938385 and WO96/26425 all describe line sensors.

BRIEF SUMMARY OF THE INVENTION

[0003] According to the invention there is provided a system as defined in appended Claim 1.

[0004] The invention further relates to a method of detecting the intrusion of moisture into insulation layer provided along a pipe wall as defined in appended Claim 7.

[0005] In general, as mentioned above, the present invention provides a system and method for detecting the intrusion of moisture into insulation, such as the intrusion of water into insulation used in a plant environment. For example, the technique can be used to enable detection of moisture within process piping insulation and for monitoring conditions, e.g. moisture and temperature, which can lead to corrosion under the insulation. A first distributed sensor line and a second distributed sensor line are positioned along a desired section of insulation, and the differential temperatures are measures across the insulation between the lines. The determination of regional changes in the differential temperatures provides an indication of a potential moisture problem in a specific region or regions of the insulation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:

Figure 1 is a schematic view of an insulated apparatus combined with a moisture detection system, according to an embodiment of the present invention;

Figure 2 is a diagrammatic representation of a processor based control system that can be used to carry out all or part of the methodology for determining the intrusion of moisture, according to an embodiment of the present invention;

Figure 3 is a cross-sectional view of an insulated vessel having spaced sensor lines, routed along a layer of insulation, for determining differential temperatures along the layer, according to an embodiment of the present invention;

Figure 4 is a view similar to that of Figure 3, but showing the formation of moisture in a specific region;

Figure 5 is a graphical representation of temperatures measured along one of the sensor lines, according to an embodiment of the present invention;

Figure 6 is a graphical representation of temperatures measured along a second sensor line, the graph illustrating temperature peaks indicative of reduced differential temperature and the potential intrusion of moisture, according to an embodiment of the present invention;

Figure 7 is a flowchart illustrating an embodiment of the methodology that can be used to determine the wetting of a region of insulation, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0007] In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

[0008] The present invention relates to a system and method for detecting and managing corrosion under insulation in insulated equipment, in particular pipes for holding and/or carrying fluids. The system operates through detection of moisture in the insulation via ongoing evaluation of differential temperatures across the insulation or partial sections of insulation surrounding the piping. This automatic, ongoing insulation evaluation affords improved risk assessments for corrosion under insulation. The ongoing evaluation also reduces the requirements for regular inspection and maintenance in, for example, a variety of plants, including oil and gas production/processing plants, refineries, chemical plants and other plants that use insulated vessels in plant operations.

[0009] Generally, distributed sensor lines, such as distributed temperature sensing system compatible sensor fibers or sensor cables are deployed through or along the insulation surrounding piping or other equipment such that the sensor lines are separated by at least a portion of the insulation layer. The distributed sensor lines enable a distributed and continuous determination of the differential temperature across the insulation between the sensor lines via, for example, distributed temperature sensing technology. An initial temperature differential is established between the sensor lines as a reference temperature differential. This enables ongoing detection of any changes in the temperature differential, which can be indicative of moisture intruding on that particular region of insulation. If, for example, a region of the insulation is wetted via intrusion of water or other wetting agent, the sensor lines detect a reduction in temperature differential for that region due to impairment of the insulating properties of the insulation resulting from the moisture.

[0010] Referring generally to Figure 1, a system 20 is illustrated as an example of a variety of systems that can be found in plant environments or other environments that use insulated equipment. In this embodiment; system 20 comprises an insulated equipment component in the form of an insulated pipe or piping 24 with a wall 26 covered by insulation 28. By way of specific example, the insulation 28 may be formed as a layer of insulation around the piping 24. At least two distributed sensor lines 30 and 32 are deployed along the piping 24 and separated by a section 34 of insulation 28. Additional distributed sensor lines can be deployed through insulation 28 if differential temperatures and moisture detection are sought along other areas of the insulated vessel or if a backup sensor system is desired for a specific application.

[0011] In many applications, the distributed sensor lines 30, 32 are deployed with fairly uniform spacing therebetween to establish a uniform reference differential temperature. The routing of the sensor lines along or through the insulation can vary from one application to another. In the embodiment illustrated, the sensor lines 30 and 32 are spaced generally uniformly and routed in a longitudinal direction along piping 24.

[0012] The distributed sensor lines 30 and 32 may comprise distributed temperature sensing compatible sensor lines coupled into a distributed temperature sensing system 36. By way of example, distributed sensor lines 30 and 32 may comprise distributed temperature sensing system compatible sensor fibers or distributed temperature sensing system compatible cables deployed along insulated vessel 22. The distributed temperature sensing system 36 and the ongoing measurement of differential temperatures along insulated vessel 22 may be automatically controlled via a control system 38. Control system 38 enables continuous measurement of temperature along each distributed sensor line 30 and 32, establishment of differential temperatures between the sensor lines, and determination of any changes in the differential temperature at any region along insulated vessel 22. Additionally, control system 38 enables the measurement of temperature and the determination of differential temperatures continuously and in real time if desired for a specific application.

[0013] An example of an automated control system 38 is illustrated diagrammatically in Figure 2. In this embodiment, automated control system 38 may be a computer-based system having a central processing unit (CPU) 40. CPU 40 may be operatively coupled to distributed temperature sensing system 36, and may comprise a memory 42, an input device 44, and an output device 46. Input device 44 may comprise a variety of devices, such as a keyboard, mouse, voice-recognition unit, touchscreen, other input devices, or combinations of such devices. Output device 46 may comprise a visual and/or audio output device, such as a monitor having a graphical user interface. Additionally, the processing of the information from distributed sensor lines 30 and 32 may be done on a single device or multiple devices at the system location, at a centralized plant location, at locations remote from the plant, or at multiple locations.

[0014] Referring generally to Figures 3 and 4, a specific example of system 20 is illustrated. In this example, insulation 28 is arranged in a layer around pipe 24 defined by the vessel or pipe wall 26. In this example, both distributed sensor lines 30 and 32 are routed generally longitudinally through insulation layer 28 with a portion of the insulation layer, i.e. insulation section 34, disposed between the sensor lines. Distributed sensor line 30 is deployed radially inward of distributed sensor line 32 generally adjacent an exterior of the wall 26 defining pipe 24. Distributed sensor line 32 is deployed proximate a radially exterior surface of insulation layer 28. However, the distributed sensor lines 30 and 32 can be deployed at different locations on or through the insulation layer 28. In this embodiment, insulation layer 28 also comprises an outer protective sheath 48, and both distributed sensor lines 30 and 32 are located radially inward of outer protective sheath 48.

[0015] The distributed sensor lines 30 and 32 can measure temperatures along their length through insulation layer 28 over, for example, the distance spanned by pipe 24. By using distributed temperature sensing system compatible fibers or cables, the system can be designed to measure temperatures up to and even higher than 200°C. Distributed temperature sensing system 36 and control system 38 are used in determining the differential temperatures between sensor lines 30 and 32 along the length of the sensor lines, e.g. along the entire length of pipe 24. If moisture intrudes into insulation 28 to form a wetted region 50, as illustrated in Figure 4, the insulating properties of the insulation layer become impaired. The impaired insulating properties reduce the differential temperature in wetted region 50, and the reduced differential temperature is detected and processed by distributed temperature sensing system 36 and control system 38. Once the change in differential temperature is detected by the system, the system can provide an audible and/or visual output via, for example, output 46 for review by an operator. The pinpointed location of a change in the differential temperature enables the operator to examine and attend to the specific region of the insulated vessel potentially experiencing the problem.

[0016] By way of example, the distributed temperature sensing system 36 and control system 38 can be used to provide continuous, real-time detection of temperatures and a determination of differential temperatures along each of the distributed sensor lines 30 and 32, as illustrated graphically in Figures 5 and 6. The shape of the graphs, of course, varies according to the positioning of sensor lines 30 and 32, the type of vessel 24, the type and temperature of fluid contained in or passing through the vessel, the constant or intermittent nature of fluid passing through the vessel, e.g. piping, 24, the type of insulation used in insulation layer 28, and other factors affecting the ultimate shape of the graphs. Accordingly, the graphical representations in Figures 5 and 6 are simply one example of temperatures, temperature differentials, and changes in temperature differentials for a heated fluid that is passed through an insulated pipe. However, the graphical representations are illustrative of the type of information provided to distributed temperature sensing system 36 and control system 38 via distributed sensor lines 30 and 32.

[0017] In this particular example, distributed sensor line 30 is deployed adjacent pipe 24, as described with respect to Figures 3 and 4. Upon passage of a heated fluid through pipe 24, distributed sensor line 30 detects and measures temperatures along the length of the insulated pipe as represented by graph peaks 52 of Figure 5. Similarly, distributed sensor line 32 detects and measures temperatures along the radially outlying region of insulation layer 28, as represented by graph peaks 54 of Figure 6. However, in wetted regions, such as wetted region 50 illustrated in Figure 4, the efficiency of the insulation layer is reduced. The reduced efficiency causes temperature increases that are detected and measured by distributed sensor line 32 in the wetted region(s) along the insulated piping. The increased temperatures, as represented by graph peaks 56, result in a reduced differential temperature between distributed sensor lines 30 and 32 for those specific regions. Accordingly, by measuring the temperatures along each distributed sensor line 30 and 32 and determining changes, e.g. reductions, in differential temperatures at specific regions, the system 20 can be used to provide an operator with indicated regions where moisture has potentially intruded into insulation 28.
An example of an implementation of system 20 and the methodology used in operating system 20 is illustrated by the flowchart of Figure 7. It should be noted, however, that this is one example of the methodology, and changes and/or additions can be made to accommodate different environments, components and application parameters. In this example, at least two distributed temperature sensor lines are initially deployed along a pipe, as illustrated by block 58. The distributed sensor lines are spaced from each other such that at least a portion of the insulation surrounding the pipe separates the distributed sensor lines, as illustrated by block 60. The distributed sensor lines can be routed along the outer extents of the insulation or through interior regions of the insulation. Additionally, the distributed sensor lines can be routed along generally straight or circuitous paths along an exterior or an interior of the pipe, depending on the specific application in which the insulated pipe is used. The spacing between the sensor lines also can be constant or can undergo changes to, for example, accommodate unique shapes of the insulated pipe.

[0018] Upon constructing the insulated pipe with the appropriate distributed sensor lines, the system is operated to enable the distributed temperature sensing system 36 to measure temperatures along each distributed sensor line 30 and 32, as illustrated by block 62. During this initial run, the temperatures gathered can be used to establish reference differential temperatures along the distributed sensor lines, as illustrated by block 64. In this particular example, the process is ongoing, e.g. heated fluid is continually run through pipe 24, and differential temperatures between the sensor lines are determined continuously and on a real-time basis, as illustrated by block 66. The temperature measurement and the determination of differential temperatures can be done along the entire length of the insulated pipe.

[0019] As the process/application continues, temperatures are continuously measured and compared to determine any changes in temperature differentials. If moisture intrudes on an area of insulation, the differential temperature changes and those changes, e.g. reductions, in differential temperature are detected by distributed temperature sensing system 36. The detected changes can be for one or more specific regions along the distributed sensor lines, as illustrated by block 68. An operator, such as a plant operator, is then able to evaluate the specific region or regions to determine whether any areas of insulation have actually become wetted, as illustrated by block 70. Depending on the extent and location of the intruding moisture, appropriate corrective action can be taken to reduce or eliminate potential corrosion under insulation, as illustrated by block 72.

[0020] The specific plant processes in which the moisture detection system is implemented can vary widely. Additionally, the shape, size and function of the insulated pipes may vary from one plant to another or from one plant section to another. The type of distributed sensor lines, e.g. fibers or cables, can vary and the specific type of insulation used for a given application can vary depending on the environment in which a process is carried out as well as the specific parameters of that process. Additionally, the specific type of distributed temperature sensor system and control system used can vary according to application requirements, available technology, and changes in technology.

[0021] Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention, as defined in the claims.

Claims

1. A system, comprising:

a pipe (24) having a wall (26) and an insulation layer (28) along said wall (26);
and

a moisture detection system comprising a distributed temperature sensing system, which comprises a first sensor line (30) and a second sensor line (32) radially spaced from each other by a portion of said insulation layer (28) and extending longitudinally along the pipe wall (26), wherein

the sensor lines (30, 32) are distributed sensor lines such as sensor fibres or sensor cables configured to respond continuously along their respective lengths to temperature; and

said distributed temperature sensing system is adapted to detect moisture in said portion of the insulation layer (28) between said sensor lines (30, 32) by determining changes in the differential temperature between the first and second sensor lines (30, 32).

2. The system of claim 1, wherein the first sensor line (30) is positioned adjacent the pipe (24) and the second sensor line (32) is positioned along an external portion of the insulation layer (28).

3. The system of claim 1, wherein the insulation layer (28) comprises an outer protective sheath, and said sensor lines (30, 32) are located radially inward of the outer protective sheath.

4. The system of claim 1, wherein the first sensor line (30) and the second sensor line (32) comprise distributed temperature sensing system compatible sensor fibers.

5. The system of claim 1, wherein the first sensor line (30) and the second sensor line (32) comprise distributed temperature sensing system compatible sensor cables.

6. The system of claim 1, wherein the distributed temperature sensing system determines changes in the differential temperature between the first and second sensor lines (30, 32) continuously in real time.

7. A method of detecting the intrusion of moisture into insulation layer (28) provided along a pipe wall (26), comprising the steps of:

deploying first and second distributed sensor lines (30, 32) such as sensor fibres or sensor cables configured to respond continuously along their respective lengths to temperature, longitudinally along said pipe wall (26) and radially spaced from each other by a portion of said insulation layer (28);

measuring differential temperatures at continuous locations between the first and second sensor lines (30, 32); and

determining changes in said differential temperatures to determine if said region of the insulation (28) is exposed to moisture.

8. The method of claim 7, wherein deploying comprises deploying the distributed sensor lines (30, 32) through the insulation (28).

9. The method of claim 8, further comprising forming the insulation (28) as a layer having an outer protective sheath.

10. The method of claim 9, wherein deploying comprises deploying the pair of distributed temperature sensor lines (30, 32) such that a first distributed temperature sensor line (30) lies proximate the pipe (24) and a second distributed temperature sensor line (32) lies proximate an exterior of the insulation layer (28).

11. The method of claim 7, wherein measuring differential temperatures comprises:

establishing an initial temperature differential; and

using the initial temperature differential as a reference temperature differential.

12. The method of claim 7, wherein measuring differential temperatures comprises determining regions in which the differential temperature is reduced as a result of exposure to the wetting agent.

13. The method of claim 7, wherein measuring differential temperatures comprises measuring continuously in time.

Ansprüche

1. System, das umfasst:

ein Rohr (24) mit einer Wandung (26) und einer Isolationsschicht (28) entlang der Wandung (26);
und

ein Feuchtigkeitsnachweissystem, das ein verteiltes Temperaturerfassungssystem umfasst, welches einen ersten Sensorstrang (30) und einen zweiten Sensorstrang (32) umfasst, die radial voneinander durch einen Abschnitt der Isolationsschicht (28) getrennt sind und sich längs entlang der Rohrwandung (26) erstrecken, wobei

die Sensorstränge (30, 32) verteilte Sensorstränge wie Sensorfasern oder Sensorkabel sind, die ausgelegt sind, kontinuierlich entlang ihrer jeweiligen Länge auf Temperatur zu reagieren; und

das verteilte Temperaturerfassungssystem eingerichtet ist, Feuchtigkeit im Abschnitt der Isolationsschicht (28) zwischen den Sensorsträngen (30, 32) durch Ermitteln von Änderungen der Differenztemperatur zwischen dem ersten und zweiten Sensorstrang (30, 32) nachzuweisen.

2. System nach Anspruch 1, wobei der erste Sensorstrang (30) an das Rohr (24) angrenzend positioniert ist und der zweite Sensorstrang (32) entlang einem Außenabschnitt der Isolationsschicht (28) positioniert ist.

3. System nach Anspruch 1, wobei die Isolationsschicht (28) einen äußeren Schutzmantel umfasst und die Sensorstränge (30, 32) radial innerhalb des äußeren Schutzmantels gelegen sind.

4. System nach Anspruch 1, wobei der erste Sensorstrang (30) und der zweite Sensorstrang (32) Sensorfasern umfassen, die mit dem verteilten Temperaturerfassungssystem kompatibel sind.

5. System nach Anspruch 1, wobei der erste Sensorstrang (30) und der zweite Sensorstrang (32) Sensorkabel umfassen, die mit dem verteilten Temperaturerfassungssystem kompatibel sind.

6. System nach Anspruch 1, wobei das verteilte Temperaturerfassungssystem Änderungen der Differenztemperatur zwischen dem ersten und zweiten Sensorstrang (30, 32) kontinuierlich in Echtzeit ermittelt.

7. Verfahren zum Nachweis des Eindringens von Feuchtigkeit in die entlang einer Rohrwandung (26) bereitgestellte Isolationsschicht (28), umfassend die Schritte:

In-Bereitstellung-Bringen des ersten und zweiten verteilten Sensorstrangs (30, 32) wie Sensorfasern oder Sensorkabel, die ausgelegt sind, kontinuierlich entlang ihrer jeweiligen Länge auf Temperatur zu reagieren, längs entlang der Rohrwandung (26) und radial voneinander durch einen Abschnitt der Isolationsschicht (28) getrennt;

Messen der Differenztemperaturen an fortlaufenden Stellen zwischen dem ersten und zweiten Sensorstrang (30, 32); und

Ermitteln von Änderungen der Differenztemperatur, um zu ermitteln, ob der Bereich der Isolation (28) einer Feuchtigkeit ausgesetzt ist.

8. Verfahren nach Anspruch 7, wobei das In-Bereitstellung-Bringen umfasst, die verteilten Sensorstränge (30, 32) durch die Isolation (28) in Bereitstellung zu bringen.

9. Verfahren nach Anspruch 8, das ferner umfasst, die Isolation (28) als Schicht mit einem äußeren Schutzmantel auszubilden.

10. Verfahren nach Anspruch 9, wobei das In-Bereitstellung-Bringen umfasst, das Paar verteilter Temperatursensorstränge (30, 32) so in Bereitstellung zu bringen, dass ein erster verteilter Temperatursensorstrang (30) nahe dem Rohr (24) und ein zweiter verteilter Temperatursensorstrang (32) nahe einem Äußeren der Isolationsschicht (28) liegt.

11. Verfahren nach Anspruch 7, wobei das Messen von Differenztemperaturen umfasst:

eine Anfangstemperaturdifferenz festzustellen; und

die Anfangstemperaturdifferenz als Referenztemperaturdifferenz zu verwenden.

12. Verfahren nach Anspruch 7, wobei das Messen von Differenztemperaturen umfasst, Bereiche zu ermitteln, in welchen die Differenztemperatur, infolgedessen, dass sie dem Benetzungsmittel ausgesetzt sind, reduziert ist.

13. Verfahren nach Anspruch 7, wobei das Messen von Differenztemperaturen umfasst, zeitlich kontinuierlich zu messen.

Revendications

1. Un système comprenant :

un tube (24) ayant une paroi (26) et une couche d'isolation (28) le long de ladite paroi (26) ; et

un système de détection d'humidité comprenant un système de détection de température distribué qui comprend une première ligne de détection (30) et une deuxième ligne de détection (32) espacées radialement l'une par rapport à l'autre par une portion de ladite couche d'isolation (28) et s'étendant longitudinalement le long de la paroi du tube, dans lequel

les lignes de détection (30, 32) sont des lignes de détection distribuées, comme des fibres de détection ou des câbles de détection configurés pour répondre continuellement à la température le long de leurs longueurs respectives ; et

ledit système de détection de température distribué est adapté à détecter l'humidité dans ladite portion de la couche d'isolation (28) entre lesdites lignes de détection (30, 32) en déterminant les changements de la température différentielle entre la première et la deuxième ligne de détection (30, 32).

2. Le système selon la revendication 1, dans lequel la première ligne de détection (30) est adjacente au tube (24) et la deuxième ligne de détection (32) est positionnée le long d'une portion externe de la couche d'isolation (28).

3. Le système selon la revendication 1, dans lequel la couche d'isolation (28) comporte une gaine de protection extérieure et lesdites lignes de détection (30, 32) sont situées radialement à l'intérieur de la gaine de protection extérieure.

4. Le système selon la revendication 1, dans lequel la première ligne de détection (30) et la deuxième ligne de détection (32) comprennent un système de détection de température distribué compatible avec les fibres de détection.

5. Le système selon la revendication 1, dans lequel la première ligne de détection (30) et la deuxième ligne de détection (32) comprennent un système de détection de température distribué compatible avec les câbles de détection.

6. Le système selon la revendication 1, dans lequel le système de détection de température distribué détermine les changements de la température différentielle entre la première et la deuxième ligne de détection (30, 32) continuellement en temps réel.

7. Un procédé de détection de l'intrusion d'humidité dans la couche d'isolation (28) prévue le long de la paroi d'un tube (26), comprenant les étapes suivantes :

déploiement des première et deuxième lignes de détection distribuées (30, 32), comme des fibres de détection ou câbles de détection, configurés pour répondre continuellement à la température le long de leurs longueurs respectives, longitudinalement le long de ladite paroi de tube (26) et radialement espacées l'une par rapport à l'autre par une portion de ladite couche d'isolation (28) ;

mesure des températures différentielles à des endroits continus entre les première et deuxième lignes de détection (30, 32) ; et

détermination des changements desdites températures différentielles pour déterminer si la ladite région de l'isolation (28) est exposée à l'humidité.

8. Le procédé selon la revendication 7, dans lequel le déploiement comprend le déploiement des lignes de détection distribuées (30, 32) à travers l'isolation (28).

9. Le procédé selon la revendication 8, comprenant en outre la formation de l'isolation (28) comme une couche ayant une gaine de protection extérieure.

10. Le procédé selon la revendication 9, dans lequel le déploiement comprend le déploiement de la paire de lignes de détection de température distribuées (30, 32) de telle sorte qu'une première ligne de détection de température distribuée (30) est située près du tube (24) et qu'une deuxième ligne de détection de température distribuée (32) est située près de l'extérieur de la couche d'isolation (28).

11. Le procédé selon la revendication 7, dans lequel la mesure des températures différentielles comprend :

l'établissement d'un différentiel de température initial ; et

l'utilisation du différentiel de température initial comme différentiel de température de référence.

12. Le procédé selon la revendication 7, dans lequel la mesure des températures différentielles comprend la détermination des régions dans lesquelles la température différentielle est réduite suite à l'exposition à l'agent mouillant.

13. Le procédé selon la revendication 7, dans lequel la mesure des températures différentielles comprend une mesure continue en temps réel.

Drawing